Introducing self-aligned dopants in semiconductor fins

Abstract

A method of introducing self-aligned dopants in semiconductor fins and the resulting device are provided. Embodiments include providing semiconductor fins on first and second portions of a substrate; forming a BSG layer on side surfaces of the semiconductor fins on the first portion of the substrate; forming a first SiN layer on the BSG layer; forming a high quality oxide layer over an upper surface of the substrate, the first SiN layer and side surfaces of the semiconductor fins on the second portion of the substrate; forming a PSG layer over the high quality oxide layer on the second portion of the substrate and side surfaces of the semiconductor fins on the second portion of the substrate; and forming a second SiN layer over the high quality oxide layer and the PSG layer.

The invention claimed is: 
     
       1. A method comprising:
 providing semiconductor fins on first and second portions of a substrate; 
 forming a borosilicate glass (BSG) layer on side surfaces of the semiconductor fins on the first portion of the substrate; 
 forming a first silicon nitride (SiN) layer on the BSG layer; 
 forming a high quality oxide layer over an upper surface of the substrate, the first SiN layer and side surfaces of the semiconductor fins on the second portion of the substrate; 
 forming a phospho silicate glass (PSG) layer over the high quality oxide layer on the second portion of the substrate and side surfaces of the semiconductor fins on the second portion of the substrate; and 
 forming a second SiN layer over the high quality oxide layer and the PSG layer. 
 
     
     
       2. The method according to  claim 1 , comprising forming the BSG layer and the first SiN layer by:
 depositing a BSG material over the substrate and the semiconductor fins; 
 depositing a SiN material over the BSG material; 
 forming a mask over the SiN material over the first portion of the substrate and the semiconductor fins on the first portion of the substrate; 
 removing the SiN material and the BSG material from the second portion of the substrate and from the semiconductor fins on the second portion of the substrate; and 
 removing the mask. 
 
     
     
       3. The method according to  claim 2 , comprising forming the mask by:
 depositing a spin-on-hardmask (SOH) material over the SiN material; 
 forming a hard mask on an upper surface of the SOH material; 
 forming a photoresist on the hard mask over the first portion of the substrate; 
 removing the hard mask, and the SOH material over the second portion of the substrate; and 
 removing the photoresist. 
 
     
     
       4. The method according to  claim 2 , further comprising:
 removing the SiN and the BSG materials from the second portion of the substrate and the semiconductor fins on the second portion of the substrate by etching to form the BSG layer and the first SiN layer. 
 
     
     
       5. The method according to  claim 4 , further comprising:
 etching the SiN layer and the BSG layer from an upper surface of the first portion of the substrate subsequent to removing the mask. 
 
     
     
       6. The method according to  claim 5 , further comprising:
 etching the SiN layer and the BSG layer on a bottom portion of the semiconductor fins to form an acute angle with the surface of the first portion of the substrate. 
 
     
     
       7. The method according to  claim 1 , comprising forming the high quality oxide layer by:
 depositing a high quality oxide material over the substrate, the first SiN layer and the semiconductor fins on the second portion of the substrate. 
 
     
     
       8. The method according to  claim 1 , comprising forming the PSG layer by:
 depositing a PSG material over the high quality oxide layer; 
 forming a mask with an opening over the first portion of the substrate; 
 removing the PSG material from the first portion of the substrate and from the semiconductor fins on the first portion of the substrate; and 
 removing the mask. 
 
     
     
       9. The method according to  claim 8 , comprising forming the mask by:
 forming a SOH material and a hard mask over the PSG material over the second portion of the substrate and the semiconductor fins on the second portion of the substrate. 
 
     
     
       10. The method according to  claim 9 , comprising removing the PSG material by:
 etching selective to the high quality oxide layer. 
 
     
     
       11. A device comprising:
 semiconductor fins on first and second portions of a substrate; 
 a borosilicate glass (BSG) layer on side surfaces of the semiconductor fins on the first portion of the substrate; 
 a first silicon nitride (SiN) layer on the BSG layer; 
 a high quality oxide layer over an upper surface of the substrate, the first SiN layer and side surfaces of the semiconductor fins on the second portion of the substrate; 
 a phospho silicate glass (PSG) layer over the high quality oxide layer on the second portion of the substrate and of the semiconductor fins on the second portion of the substrate; and 
 a second SiN layer over the high quality oxide layer and the PSG layer. 
 
     
     
       12. The device according to  claim 11 , wherein the BSG layer have a thickness of 2 nanometer (nm) to 5 nm. 
     
     
       13. The device according to  claim 11 , wherein the first SiN layer have a thickness of 2 nm to 5 nm. 
     
     
       14. The device according to  claim 11 , wherein the high quality oxide layer have a thickness of 1 nm to 5 nm. 
     
     
       15. The device according to  claim 11 , wherein the PSG layer have a thickness of 2 nm to 5 nm. 
     
     
       16. The device according to  claim 11 , wherein the second SiN layer have a thickness of 1 nm to 5 nm. 
     
     
       17. A method comprising:
 providing semiconductor fins on first and second portions of a substrate; 
 depositing a BSG material over the substrate and the semiconductor fins; 
 depositing a SiN material over the BSG material; 
 forming a first mask over the SiN material over the first portion of the substrate and the semiconductor fins on the first portion of the substrate; 
 etching the SiN material and the BSG material from the second portion of the substrate and from the semiconductor fins on the second portion of the substrate; 
 removing the first mask; 
 etching the SiN material and the BSG layer from an upper surface of the first portion of the substrate; 
 forming a high quality oxide layer over an upper surface of the substrate, the first SiN material and side surfaces of the semiconductor fins on the second portion of the substrate; 
 depositing a PSG material over the high quality oxide layer; 
 forming a second mask with an opening over the first portion of the substrate; 
 etching the PSG material, selective to the high quality oxide layer, from the first portion of the substrate and from the semiconductor fins on the first portion of the substrate; 
 removing the second mask; and 
 depositing a second SiN material over the high quality oxide layer and the PSG layer. 
 
     
     
       18. The method according to  claim 17 , comprising forming the first mask by:
 depositing a spin-on-hardmask (SOH) material over the SiN material; 
 forming a hard mask on an upper surface of the SOH material; 
 forming a photoresist on the hard mask over the first portion of the substrate; 
 removing the hard mask, and the SOH material over the second portion of the substrate; and 
 removing the photoresist. 
 
     
     
       19. The method according to  claim 17 , further comprising:
 etching the SiN material and the BSG layer on a bottom portion of the semiconductor fins to form an acute angle with the surface of the first portion of the substrate. 
 
     
     
       20. The method according to  claim 17 , comprising forming the second mask by:
 forming a SOH material and a hard mask over the PSG material over the second portion of the substrate and the semiconductor fins on the second portion of the substrate.